Steve Jobs:
While he was technically fired, there is no doubt Jobs told all his bosses to stick it during his first term at Apple. He would go on to found 2 multi-million dollar companies, then come back to save the company that he founded and was fired from.

Gordon Moore, Robert Noyce, Eugen Kleiner:
The three left Shockley Semiconductor Laboratory to help form fairchild semi-conductor and later to form intel and Kleiner Perkins.

Lee Iacocca:
Fired from ford for his disagreements with the boss, he would join and save Chrysler. "If you can find a better car, buy it."

Helped Gap grow into a behemoth over 19 years of dedication. Got fired. Refused to sign a non-compete and gave up his severance package. Joined J. Crew. Hired a ton of execs away from Gap and grew J. Crew into a behemoth.